8.2 Font Files

The gtroff font format is roughly a superset of the
ditroff font format (as used in later versions of AT&Ttroff and its descendants). Unlike the ditroff font
format, there is no associated binary format; all files are text
files.31 The font files for device name are stored in a directory
devname. There are two types of file: a device description
file called DESC and for each font f a font file
called f.